Apparatus for starting electric motors.



S. B. PAIN'E. APPARATUS FOR QTABTING ELECTRIC MOTORS. APPLICATION, PIL DHAY 2a, 1909.

940 55 0. Patented N0v.

Witnesses:

Inventor Sidney B. Paine,

may.

lil-

6, switch losing connected in series SIDNEY B. PAINE, Q NEWTON,IiidSSACE'USETTS, ASSIGNOR T0 GENERAL ELECTRIC GQEIPANZ, CORPORATION OFNEW! YORK.

WPABATU$ 'E'QR STARTING- ELECTRIG MOTORS.

Specification of Letters Eatent.

Patented 31 d,

application filed May 28, 1969. serial lilo. 498,948.

VMassachusetts, have invented certain new and useful lmprovements inApparatus for Starting Electric Motors, of which the following is aspecification.

My invention relates to the starting of a plurality of electric motors,and has for its object on improvement in the apparatus used in such aconnection.

ll accomplish the object of myinvention by the employment of certainforms of apparatus and connections pertaining thereto, the novelfeatures of my invention being pointed out with more particularity inthe claims annexed to and forming a part of this specification. 4 For afurther understanding of my invention reference may be had to theaccompanying drawing, which shows diagrannnatically the connections andapparatus which I employ.

1 is a source of voltage which is illustrated as bein athree-phase'generator connected by con uctors 2 to a suitable/switchingdevice 3, which is shownas being of the usual type of startingcompensator employed with induction motors. Conductors i, 5 and 6 areshown also connected to this starting device, the starting device beingconnected between the source and the conductors. The essential featuresof this starting device consist of a plurality of movable contacts 7,which may he made to engage with stationary contacts 8 and 9. Whencontacts 7 are in connection with contacts 8, conductors l, 5 and 6 areenergized from a portion of the voltage of the source; this beingaccomplished by suitable compensator windings 10, which are connectedacross conductors 2 and have connected to them ta 5 11 which energizeconductors d, 5 and 6 in the well known manner. When contacts 7 are incontact with contacts 9, the conductors l, 5 and 6 are energized fromfull voltage from the source, loses 12. losing placed in serice withthese conductors in the usual man'- ner. p

A plurality oi motors 13, as shown, are connected in parallel toconductors d, 5 and lac-tween motor and the conductors, These switchesare diagraminaticaldv illus rated as being of the usualoil-insulatedtype, and have in connection with them an electromagneticunder-voltage tripping device which consists of a coil 15, and trippingdevice 16, which, in conjunction with theusual mechanism, not shown,opens switch ll when the voltage across coils 15 is lower than apredetermined amount. Connected in series with coil 15 is shown aresistance 17, the coil and resistance being connected by conductors 18to conductors 2,- either directly as shown or through a suitabletransformer. Thus, 'l'he energization of these coils will be independentof the position of the starting device 3. @ondactors 18 are shown havingplaced in 'sc 1 1 for purposes of oat w placed in series wr In additionto the undo gs til, devices, in connection with switches 1% are alsoshown overload tripping devices 20. These devices consist of a magneticcore which will be raised when a current above a predetermined amountflows in coil 22,

shown in operative relation with core 21,

and is connected in series with one of the phases of the 'circuitsleading to the motor. When the core' has been raised a certain amountcontact 23 will make contact-with contacts 24 and thus short circuitcoil 15 of the under-voltage tripping device, and cause the switch ll toopen. In operative relation with movable core 21 is shown a dashpotmechanism 25, which retards the 1110- tion of the overload device sothat it will require-a considerable period of time before-it makescontact with contacts 24:" The object of this mechanism is that when aninduction motor is starting, it requires a current considerably inexcess of the usual current which it takes when running. If the overloadtripping devices are adjusted to be actuated slowly and notinstantaneously when the motors are started with such excessive currentas would normally cause these devices to be actuated, their movement isadjusted so as to be of such slow nature that there will not hesuflicient time for them to trip the oil switches before the heavystarting current becomes reduced through the speeding up of themot-01's.

- The operation of my apparatus will then be as follows Nhen it isdesired to start up a plurality of motors the under-voltage by LettersPatent of the United States is,-

tripping devices are connected up as shown, so that in case the voltagefrom the source is below normal, switches 14 will be open and it will beimpossible to start motors 13. The starting device 3 is then placed insuch a position'that Contacts 7 are in connection with contacts 8, andconductors 4, 5 and 6 are, therefore, energized with a portion of thevoltage from the source. The motors will start up with a currentinexcess of the normal running current and. the overload devices 20 willbegin to be actuated, but their movement will be. comparatively slow,because of the action of the dash-pot mechanism 25. After the motorshave speeded up the usual amount, switching device 3 will be so operatedthat contacts 7 are in connection with contacts 9 and the motors will beenergized with the full voltage from the source. The current flowing inthe coils of the overload tripping devices will be greatly diminishedand the cores of these devices will tend to move downward due to theaction of spring mechanism, not shown. The running conditions will nowprevail for the motors. If the voltage on the line decreases below acertain amount, oil switches 14 will be opened and if an overload occurson any motor, the switch in series with it will be opened to the actionon' the overload tripping device.

WhileI have shown my invention as applied to a certain form of apparatusand connections therefor, it is obvious that a number of such forms andconnections will be obvious to those skilled in the art, and I seek inthe appended claims to cover all such forms and connections which willbe in the spirit of my invention. a

What I claim as new and desire to secure 1. In a system of distribution,a sourceof voltage, a plurality of conductors, a starting deviceconnected between the source and the conductors for simultaneouslyenergizin the conductors alternately with a portion 0% the voltage'fromthe source and with full voltage from the source, a plurality of motorsconnected in parallel to the conductors, switches connected in seriesbetween the motofs and the conductors, overload tripping devices for theswitches, under-voltage electromagnetic tripping devices for theswitches and conductors connecting said tripping devices to the sourceindependently from the starting device.

2. In a system of distribution, a source of voltage, a plurality ofconductors, a compensator connected between the source and theconductors adapted in one position to energize the conductors with aportion of the voltage from the source and in another position with thefull voltage from the source, a plurality of motors connected inparallel to the conductors, switches connected in series between themotors and the conductors, undervoltage electromagnetic tripping devicesfor the switches, conductors connecting said tripping devices to thesource so as to be independent of the position of the compensator, andmeans operative upon an overload for actuating said tripping devices.

3. In a system of distribution, a source of voltage, a plurality ofconductors, a compensator connected between the source and theconductors adapted in one position to energize the conductors with aportion of the Voltage from the source and in another position with thefull voltage from the source, a plurality of .motors connected inparallel to the conductors, switches connected in series between themotors and the conductors, under-voltage electromagnetic trippingdevices for the switches, conductors connecting said tripping devices tothe source so as to be independent of the position of the compensator,and means operative upon an overload to short-circuit said v trippingdevices after a predetermined time.

In witness whereof, I have hereunto set my handthis 26th day of May1909.

SIDNEY B. PAINE. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

